Variable used without being declared

[Spiff59]

This runs fine in 3.3.8.1 and did also as far as Beta 8 (and maybe later), but has not at least since beta 13 and through Beta 16.

;Global $hWnd = 0

Global $dpi = GetDPI_Ratio()
MsgBox(0,"",$dpi)

Func GetDPI_Ratio()
    Local $hWnd = 0
    Local $hDC = DllCall("user32.dll", "long", "GetDC", "long", $hWnd)
    Local $aRet = DllCall("gdi32.dll", "long", "GetDeviceCaps", "long", $hDC[0], "long", 90)
    Local $hDC = DllCall("user32.dll", "long", "ReleaseDC", "long", $hWnd, "long", $hDC)
    If $aRet[0] = 0 Then $aRet[0] = 96
    Return $aRet[0] / 96
EndFunc

You can comment out the local declare of $hWnd and toggle in the Global, and still get the "Variable used without being declared" error on $hWnd.  Did I overlook something in the release notes?

Edited August 14, 2013 by Spiff59

[jaberwacky]

Declaring $hDC as local twice triggered the error it seems, but it shouldn't have.  I think.

[Jos]

This doesn't trigger the error any more (as jaberwocky6669 already mentioned):

Global $dpi = GetDPI_Ratio()
MsgBox(0,"",$dpi)

Func GetDPI_Ratio()
    Local $hWnd = 0
    Local $hDC = DllCall("user32.dll", "long", "GetDC", "long", $hWnd)
    Local $aRet = DllCall("gdi32.dll", "long", "GetDeviceCaps", "long", $hDC[0], "long", 90)
    $hDC = DllCall("user32.dll", "long", "ReleaseDC", "long", $hWnd, "long", $hDC)
    If $aRet[0] = 0 Then $aRet[0] = 96
    Return $aRet[0] / 96
EndFunc

Edited August 13, 2013 by Jos

[Spiff59]

Oops! That bug has been in production for a year.

Strip off the second "Local" from the $hDC variable and it works fine.

Thank you.

Although, I agree, the resulting error I got does seem odd.

[trancexx]

The error should be "Can not initialize a variable with itself." and it should be on last $hDC on that line. This is bug.

[kylomas]

This works

func _1()

    local $t = 1
    local $t = 1

endfunc

>"C:\Program Files (x86)\AutoIt3\SciTE\AutoIt3Wrapper\AutoIt3Wrapper.exe" /run /beta /ErrorStdOut /in "C:\Users\ADMIN010\Desktop\qqqq.au3" /UserParams    
+>15:28:37 Starting AutoIt3Wrapper v.2.1.0.33    Environment(Language:0409  Keyboard:00000409  OS:WIN_7/Service Pack 1  CPU:X64 OS:X64)
>Running AU3Check (3.3.9.16)  from:C:\Program Files (x86)\AutoIt3\beta
+>15:28:37 AU3Check ended.rc:0
>Running:(3.3.9.16):C:\Program Files (x86)\AutoIt3\beta\autoit3.exe "C:\Users\ADMIN010\Desktop\qqqq.au3"    
--> Press Ctrl+Alt+F5 to Restart or Ctrl+Break to Stop
+>15:28:38 AutoIT3.exe ended.rc:0
>Exit code: 0    Time: 2.924

Was the problem above because the same variable being re-declared was also used within the statement?

[Spiff59]

Was the problem above because the same variable being re-declared was also used within the statement?

Nice find, that does seem to be the issue.

And the first variable in the line will be flagged as the error, even though it is not: 

local $x
local $y
local $x = 1 + $y + $x

[kylomas]

I think this is what trancexx meant by

and it should be on last $hDC on that line

[Melba23]

Hi,

Just for interest, AU3Check picks up the error (in the correct place) when used with the recommended parameters:

#AutoIt3Wrapper_Au3Check_Parameters=-d -w 1 -w 2 -w 3 -w- 4 -w 5 -w 6 -w- 7

Local $x
Local $y
Local $x = 1 + $y + $x

M23

[kylomas]

Confirmed, was taking whatever he default is

#AutoIt3Wrapper_Au3Check_Parameters=-d -w 1 -w 2 -w 3 -w- 4 -w 5 -w 6 -w- 7

_1()

func _1()

    local $t = 1
    local $t = 1

endfunc

Gives

>"C:\Program Files (x86)\AutoIt3\SciTE\AutoIt3Wrapper\AutoIt3Wrapper.exe" /run /beta /ErrorStdOut /in "C:\Users\ADMIN010\Desktop\yy.au3" /UserParams    
+>11:29:06 Starting AutoIt3Wrapper v.2.1.0.33    Environment(Language:0409  Keyboard:00000409  OS:WIN_7/Service Pack 1  CPU:X64 OS:X64)
>Running AU3Check (3.3.9.16)  params:-d -w 1 -w 2 -w 3 -w- 4 -w 5 -w 6 -w- 7  from:C:\Program Files (x86)\AutoIt3\beta
"C:\Users\ADMIN010\Desktop\yy.au3"(8,17) : warning: $t already declared/assigned
    local $t = 1
~~~~~~~~~~~~~~~~^
"C:\Users\ADMIN010\Desktop\yy.au3"(7,17) : warning: $t: declared, but not used in func.
    local $t = 1
~~~~~~~~~~~~~~~~^
C:\Users\ADMIN010\Desktop\yy.au3 - 0 error(s), 2 warning(s)
->11:29:06 AU3Check ended. Press F4 to jump to next error.rc:1
>Running:(3.3.9.16):C:\Program Files (x86)\AutoIt3\beta\autoit3.exe "C:\Users\ADMIN010\Desktop\yy.au3"    
--> Press Ctrl+Alt+F5 to Restart or Ctrl+Break to Stop
+>11:29:06 AutoIT3.exe ended.rc:0
>Exit code: 0    Time: 1.319

The second error look kind of funny but makes sense because the variable does not exist due tothe first error.

edit: Should'nt the first declaration be OK and the "already declared / assigned" error ocurr on the second declaration?

Edited August 14, 2013 by kylomas

[Spiff59]

It appears we've fleshed out the details that trancexx didn't elaborate on, and show post 5 hit the nail on the head.

Edit: Some of the above are "compiler" warnings, and some execution errors...  Think someone will fix so that correct message shows on correct variable without creating a Bugtracker?

Edited August 14, 2013 by Spiff59

[trancexx]

This works

func _1()

    local $t = 1
    local $t = 1

endfunc

>"C:\Program Files (x86)\AutoIt3\SciTE\AutoIt3Wrapper\AutoIt3Wrapper.exe" /run /beta /ErrorStdOut /in "C:\Users\ADMIN010\Desktop\qqqq.au3" /UserParams    
+>15:28:37 Starting AutoIt3Wrapper v.2.1.0.33    Environment(Language:0409  Keyboard:00000409  OS:WIN_7/Service Pack 1  CPU:X64 OS:X64)
>Running AU3Check (3.3.9.16)  from:C:\Program Files (x86)\AutoIt3\beta
+>15:28:37 AU3Check ended.rc:0
>Running:(3.3.9.16):C:\Program Files (x86)\AutoIt3\beta\autoit3.exe "C:\Users\ADMIN010\Desktop\qqqq.au3"    
--> Press Ctrl+Alt+F5 to Restart or Ctrl+Break to Stop
+>15:28:38 AutoIT3.exe ended.rc:0
>Exit code: 0    Time: 2.924

Was the problem above because the same variable being re-declared was also used within the statement?

The code that you show is unrelated to the issue from OP. Why do you think there is connection?

The problem here are Jon's interventions to the core code related to tokens evaluation. You see, every line of the code is initially transformed to set of tokens and then evaluated later when the code is executed. When the line that goes like this:

Local $x = $x

...is encountered the engine then tries to find reference to x variable in internal variables storage. If the variable isn't found the new one is created. Then parser hits equal sign on the line and evaluates what's right of it. If during that process it finds reference to the same variable (name) it produces error to prevent any possible race condition that assigning variable with the value of itself could produce. You can see this clearly if you set MustDeclareVars option.

One of the problems that I encountered when adding optionality for dollar sign variable-name prefix was how to reference functions named the same as variables. The solution was to invent special kind of tokens called vague tokens and a method that would hide variables and left only functions visible to the parser. In order to this correcly I had to force MustDeclareVars option, even if user didn't specify it explicitly, when line of code like I posted here is evaluated.

The cange was sensible and should have been part of AutoIt since day one, but no one particularly cared anyway. It was Valik's job to doccument the change and for whatever reason (well, the reasons are known to be fair) he didn't.

Then recently Jon took charge of things and started removing parts of the code. But you can't always remove things you don't really understand and not have issues sometimes. My guess is that he removed vague tokens but forgot to remove parts of the code related to hiding variables during evaluation. That's why wrong error is produced and shown to the user.

So once again, this is bug. And it has nothing to do with the code that you posted.

[kylomas]

@trancexx - Thank You for the explanation, and, yes, it has nothing to do with $hWnd

[mLipok]

Hi,

Just for interest, AU3Check picks up the error (in the correct place) when used with the recommended parameters:

#AutoIt3Wrapper_Au3Check_Parameters=-d -w 1 -w 2 -w 3 -w- 4 -w 5 -w 6 -w- 7

Local $x
Local $y
Local $x = 1 + $y + $x

M23

 

 

Can this be used with new #pragma directive ?

[Melba23]

mlipok,

Can what be used? #pragma directives deal with compilation, not syntax checking, so I do not understand what you mean.

M23

[mLipok]

Poorly expressed.

Rather than the #AutoIt3Wrapper can I use #pragma directives relevant to the setting of parameters for Au3Check.

[Melba23]

mlipok,

No. As I explained above, the #pragma directives deal with compilation, not syntax checking - look at the list of available directives in the Help file.

M23

[mLipok]

thanks for twice a detailed explanation.